Models And Computations For The Process Of Laser Ignition Of Energetic Materials

Under the current experiment conditions, it is difficult to completely understand the characteristics of laser ignition of energetic materials because of instantaneity and complexity of the process. Thus, researchers attach widespread importance to the method of numerical simulation. The purpose of this dissertation is to analyze characteristics of laser ignition of energetic materials by the mathematic models and numerical simulation.The main points in the dissertation are as follows:(1) Laser absorbed by the material can be transformed into heat energy. First, the analytic solution of heat-conduct equation is given in this dissertation. Then, the analytic functions of approximative ignition time and energy are obtained.(2) A transient, one-dimensional solid-phase model for laser ignition based on thermal mechanism is developed in this dissertation, and a two-dimensional model based the former work is established. Influences of laser energy distribution, reactant concentration, heat convection and radiation factors are considered in the two-dimensional model. The partial differential equation is solved by Alternating Direction Implicit algorithm. Influences of laser pulse width, beam radius, thermal conduction and depth absorption coefficient on ignition of Mg/NaNO3 are analyzed.(3) Using heat-transmission, mass-transfer and optics theories, a gas-phase reaction model about the process of laser ignition is developed. The partial differential equations are solved by stable and precise Crank-Nicolson algorithm. Regarding RDX as the research object, influences of laser power and pressure on the process of laser ignition are investigated.(4) Regulations of laser ignition are analyzed and compared by the models developed in this dissertation. Results show that they can predict the ignition characteristics of energy material in a certain range.